@RealGhost- I agree with what you are saying about zombies not being possible in the sense that they are the "living dead" and hunger for brains. That being said, it is entirely possible with today's science to re-animate (not bring to life, just make it move again) dead flesh using electricity. It could be possible in the future to send controlled impulses through the musculature of a dead body and animate the corpse in that fashion. If that were to happen, there could very possibly be dead walking being controlled by a processor of some sort or even being remotely controlled by a living person. I think that could be classified as a zombie.

I disagree with what was said about the portal gun not being possible. The law of conservation of energy is broken every day by black holes. If energy cannot be created or destroyed then what happens to the energy that a black hole consumes? The fact of the matter is that we don't know what happens to the energy beyond the event horizon of a black hole. Effectively, the energy passing beyond the event horizon is being destroyed because it no longer falls within our understanding of physics.

Also, stating that nothing can travel faster than the speed of light is asinine when recently a particle (neutrino) was found that does travel faster than the speed of light. While there are people trying to refute the claim based on the energy levels of the particles, multiple runs at varying distances have been conducted with the same results. Back on the black hole reference, if nothing can travel faster than the speed of light, then it stands to reason that nothing can have an effect on space that is stronger than the speed of light would be it it were converted to mass, but not even light can escape a black hole.

Not too many years ago, there were some scientists investigating the possibility of a "wormhole" which would effectively be what the portal gun creates. The 2 portals are the openings to a wormhole that bridges the gap between 2 points in space.